Production of hydrogenation derivatives of dypnone



Patented Apr. 18, 1950 UNITED STATES i ATENT OFFICE PRODUCTION OFHYnRoGENA'rIoN DERIVATIVES F DYPNONE Ernest Joseph..Li1sh,, Wimbledon;London, Eng'= land, assignorj to A. BoakeRoberts and Com pany' Limited;London, England,- a' British coni- No Drawing; Amllication May 10,1948,; Serial No. 26,247. In Great BritainaMay 15, 1947 11 Claims.

This invention relates to a, process wherebynhyldrogenationderivativesof dypnone, i. e. dihydrodypnone and. dihydrodypnol, may beproduced direct from acetophenone ona commercial scale, thus makingavailable. products which havebeen found. to have outstanding propertiesas plasticisers and .for other purposes.

It has beenproposed hitherto to heat acetophenone with hydrogen-iodideand phosphorus;

at130-150" C. (Graebe B volume '7, page. 1625) and this treatmentbroughtabout the formation.

of hydrogenated dypnone, .but obviously such; a process is not acommercial proposition.

It: hasHalso-been proposed. (see Reactions 0t Hydrogen? icy-Homer Adkinsl937, page. 50) to hydrogenate; acetophenone with: the aid of a nickelcatalyst at temperatures of 110450 C. under pressure, and under. these.conditions phenyljmethyl. carbinol has been produced.

It is also. known that at a somewhat: higher temperature (175 C.) ethylbenzeneis formed:

at acommercial rate of formation and it was.

natural assumption tomake that any; attempt.

to form-dihydrodypnone. bydirecthydrogenation of acetophenone would leadeither to the. format-.- tiOHgOf the carbinol or ethylbenzeneiormixturesl of the two.

The surprising discovery has. now been. made. however, that at:a stillhigher temperatureranga than that most favourable to the. formation of.

ethyl benzene, and in the actual trials made-using a rapid current. ofhydrogen at atmospheric pres sure and a nickel catalyst, acetophenonemay be hydrogenated with the formation of.on1-y negli gible amounts ofphenyl methyl carbinol and ethyl benzene, but with the formation notidihydrop dypnone inalmost quantitative yields." The rate: of formationof dihydrodypnone commences to. be, appreciable under the aboveconditions at 160. C. and assumes commercial proportions be.

tween 1809 C..and the; decompositiontpointat 250 C. Itwill-beappreciated that=the:actualtemperature ranges given in thethreecases cited abovewilhdepend upon the catalyst chosen.

It has further been foundthat when the con-- version of acetophenone todihydrodypnone-has.-

reached a maximum, if the temperature; be. low.-

ered .to 70 to. 100 C.v and. the hydrogenation con tinued, other thingsremaining the, same, thfildihydrodypnone is convertedlinto.dihydrodypnoh- The above reactions, may be. represented. as follows:

The invention appears to dependupon' the pro ductionof dypnone and its,practically simul taneous hydrogenation before any appreciablepolymerisation can take place, the hydrogenated product being stable. Itwas found that if acetophenone. is heated in the. presence of a nickclfcatalyst Without hydrogen, condensation. of two molecules ofacetophenone takes placewith the. formation of commercial'yields'ofdypnona. It"; was found, however, .thatunder the most favour,- able'conditions considerable" polymerisation off the dypnone occurred and. inpractice. as ,much, as 12% ofdidypnone and. resin wasobtained;

The invention is not based on any. theory; of."

' what actually occurs during the reaction but is based on the discoverythat if acetophenone is heated under conditions. which arevconducivevtocondensation with. the continuous. removal. of. thewater formed thuseiiectingtthe formation of dypnone and sufiicient hydrogenis-introduced,to. reduce dypnone as fast as it is formed to; dihydrodypnone, then thelatter will be-produced; in almost quantitative yields.

According to. the present invention, therefore;

a process forthe production of'hydrogenationr derivatives of dypnonefrom acetophenone comprises the step of heating the acetophenone at a,temperature of'160 to 250 Ci in thepresence' of, a catalyst ashereinafter specifiedf and immune ling hydrogen-at a sufiicientpartialpressure" to is dependent upon thesuccessful syncl'ironi-sation of therate of dypnoneformation wit-h the rate of hydrogenation so that dypnonedoes notac cumulatei in the products-of reaction; otherwise resin isformed: Gne conven-ientway'in-which" this essential synchronisationmaybe efiectively maintained is by conducting the hydrogenation in arapid current'of"'hydrogen'- at atmospheric pressure commencingthereaction'at a-tempera= tureconsiderably abovethe temperature at whichphenyl methyl carbinol isprincipally formed but below that most suitablefor dypnone condensation. Thus, a suitable commencing temperature is180-190 C. The temperature may be raised later to about 250 C.

The dihydrodypnone may be isolated from the reaction products and usedas such by removing the small amount of unchanged acetophenone, e. g. bysteam distillation. Alternatively, as indicated above, thedihydrodypnone may be further hydrogenated without previous isolationsimply by reducing the temperature to 70 to 100 C. when the conversionof acetophenone to dihydrodypnone has reached a maximum, the processbeing otherwise continued but preferably with mechanical agitation.

On the other hand, the dihydrodypnone may be isolated and submitted tohydrogenation in a separate operation at superatmo-spheric pressure at atemperature of '70 to 100 C. or by the ketone reduction ofdihydrodypnone in the presence of an alcohol such as isopropyl alcoholand an aluminium alkoxide such as aluminium isopropoxide until no moreacetone is formed.

Where for any reason the presence of polymerisation products of dypnoneis not a disadvantage, it is quite feasible from a commercial point ofView to condense acetophenone to dypnone using nickel as condensingagent, and subsequently to reduce it by other chemical means, inparticular by hydrogenation. The dypnone obtained in this way, however,has been found to be associated with 12% of didypnone and resin. Thefollowing examples illustrate the production of dihydrodypnone and itsfurther hydrogenation to dihydrodypnol.

Example I 500 grams of acetophenone were heated in the presence of 40grams of nickel catalyst in a rapid current of hydrogen to a temperatureof 180- 190 C. for 8 hours. The water was removed through an aircondenser in the form of steam in a current of hydrogen and condensed. Aproduct was obtained having a melting point of 32-34 C.; this producthad the following composition:

Per cent Unchanged acetophenone 12 Dihydrodypnone 80 Dypnone 6 Resin", 2

The unchanged acetophenone was removed by steam distillation and wasfound to contain 10% of phenyl methyl carbinol and 2-5% ethyl benzene. 1

As the unchanged acetophenone and also the dypnone can be recycled inthe process, it will be seen from the above figures that the actualyield of dihydrodypnone is something of the order of 90%. The importantfeature about the above figures is the small production of resin.

, Example II i mostly of dihydrodypnol (1 hydroxy 1.3 diphenyl butane).Any unchanged acetophenone can be removed before cooling to 70 C. orremoved after hydrogenation as phenyl methyl carbinol. From the original10 lbs. acetophenone about 8 lbs. of dihydrodypnol were produced.

Example III 10 lbs. of dihydrodypnone and 1b. nickel catalyst werecharged to a closed autoclave and heated to 70 C. with mechanicalagitation in a hydrogen atmosphere raised to a pressure of lbs. Hydrogenwas rapidly absorbed and about 9 lbs. of dihydrodypnol were obtained.Some diphenyl butane was produced, about 5% at 70 C. and about 15% at100 C., the exact amount varying with the activity of the nickelcatalyst.

Example IV Dihydrodypnone can be hydrogenated to dihydrodypnol by othermethods commonly employed in the hydrogenation of ketones.

Thus, 10 lbs. of dihydrodypnone were charged to a still fitted with areflux condenser and overflow condenser. 4 lbs. of isopropyl alcohol and4 ozs. of aluminium isopropoxide were added and the whole heated toboiling point. From the top of the reflux condenser acetone was obtainedand when no more acetone could be obtained the contents of the stillwere found to consist essentially of dihydrodypnol. No diphenyl butanecould be detected in this method of hydrogenation.

Dihydrodypnone is a crystalline solid with a melting point of 72 C. anda boiling point of C. at 2 mm. pressure. It is practically insoluble inwater but soluble in most organic solvents, from which it is readilycrystallised. It is stable to heat, light and water, and unlike esterswhich are used extensively as plasticisers, it is not attacked byhydrolysing agents such as water and dilute alkalies. It is compatiblewith polyvinyl chloride up to 30%, polystyrene up to more than 20%, andcellulose acetate up to 10%, and polyvinyl acetate up to 10 It is moreinsoluble in water and more stable than dimethyl phthalate while havingadequate light and heat stability and low volatility. It is also capableof being used in association with other plasticisers which conferspecial properties such as the non-inflam mable properties conferred bytricresyl phosphate. Dihydrodypnol, while having similarly advantageousproperties as a plasticiser, has the further advantage of being liquidat atmospheric temperatures so that for certain purposes it hasadvantages over the dihydrodypnone.

I claim:

1. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises heating the acetophenone at atemperature of to C. in the presence of a finely divided nickel catalystin' a rapid current of hydrogen at atmospheric pressure, and finallyraising the temperature to about 250 C.

2. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises heating the acetophenone at atemperature of 180 to 190 C. in the presence of a finely divided nickelcatalyst in a rapid current 01 hydrogen at atmospheric pressure, finallyraising the t mperature to about 250 C., and isolating dihydrodypnonefrom the reaction products.

3. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises heating the acetophenone at atemperature of 180 to 190 C. in the presence of a finely divided nickelcatalyst in a rapid current of hydrogen at atmospheric pressure, raisingthe temperatur to about 250 C., and when the formation of dihydrodypnonehas reached a maximum, reducing the temperature to 70 to 100 C.,continuing the introduction of hydrogen, and isolating dihydrodypnolfrom the reaction products.

4. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises the step of heating at approximatelyatmospheric pressure the acetophenone at a temperature of 150 to 250 C.in the presence of a finely-divided nickel. catalyst, introducing excesshydrogen and removing water vapor from the reaction vessel as fast as iti formed.

5. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises the step of heating at approximatelyatmospheric pressure the acetophenone at a temperature of 160 to 250 C.in the presence of a finely-divided nickel catalyst, and introi ducinghydrogen in sufiicient excess to remove water vapor from the reactionvessel as fast as it is formed.

6. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises the step of heating at approximatelyatmospheric pressure the acetophenone at a temperature of 160 to 250 C.in the presence of a finely-divided nickel catalyst, introducinghydrogen in sufficient excess to remove Water vapor from the reactionvessel as fast as it is formed, and isolating dihydrodypnone from thereaction products.

'7. A process for the production of hydrogenation derivatives of dypnonefrom acetophen-one which comprises heating at approximately atmosphericpressure the acetophenone at a temperature of 160 to 250 C. in thepresence of a finely-divided nickel catalyst, introducing excesshydrogen, removing water vapor from the reaction vessel as fast as it isformed, and when the formation of dihydrodypnone has reached a maximum,reducing the temperature to 70 to 100 C., continuing the introduction ofhydrogen, and isolating dihydrodypnol from the reaction products.

8. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises heating at approximatel atmosphericpressure the acetophenone at a temperature of 160 to 250 C. in thepresence of a finely-divided nickel catalyst, introducing hydrogen insufficient excess to remove water vapor from the reaction vessel as fastas it is formed, and when the formation of dihydrodypnone has reached amaximum, reducing the temperature to to C., continuing the introductionof hydrogen, and isolating dihydrodypnol from the reaction products.

9. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprises heating at approximately atmosphericpressure the acetophenone at a temperature of to 250 C. in the presenceofca finely-divided nickel catalyst, introducing hydrogen in sufiicientexcess to remove water vapor from the reaction vessel as fast as it isformed, isolating the dihydrodypnone from the reaction products,treating it with hydrogen at superatmospheric pressure at 70 to 100 0.,and separating dihydrodypnol from the reaction products.

10. A process for the production of hydrogenation derivatives of dypnonefrom acetophenone which comprise heating at approximately atmosphericpressure the acetophenone at a temperature of 160 to 250 (3., in thepresence of a. finely-divided nickel catalyst, introducing hydrogen insufficient excess to remove water vapor from the reaction vessel as fastas it is formed, isolating dihydrodypno-ne from the reaction products,submitting the dihydrodypnone to reduction with an aluminum alkoxide inthe presence of a mon-ohydric alcohol and separating di hydrodypnol fromthe reaction products.

11. A modification of the process as claimed in claim 4, wherein theacetophenone is heated in the presence of the catalyst Without theintroduction of hydrogen, wherein the dypnone thus produced is thensubmitted to hydrogenation.

ERNEST JOSEPH LUSH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,334,100 Ipatieff et a1. 1- Nov.9, 1943 2,451,350 Mottern Oct. 12, 1948 OTHER REFERENCES Harries,Annalen, vol. 330, 232-3 (1904).

Mastagli, Annales de Chemie, Ser. 11, vol. 10, 362-5 (1938),

Komatsu et al., Rec. 'Irav. Chim., vol. 57, 586-90 (1938).

Covert et al., Jour. Am. Chem. $00., vol. 54, 1651-9 (1932).

Darzens, Comptes Rendus, vol. 139, 868-9 (1904).

Ipatiefi et al., Chem. Abs., v01. 34, 995 (1940).

1. A PROCESS FOR THE PRODUCTION OF HYDROGENATION DERIVATIVES OF DYPNONE FROM ACETOPHENONE WHICH COMPRISES HEATING THE ACETOPHENONE AT A TEMPERATURE OF 180 TO 190*C. IN THE PRESENCE OF A FINELY DIVIDED NICKEL CATALYST IN A RAPID CURRENT OF HYDROGEN AT ATMOSPHERIC PRESSURE, AND FINALLY RAISING THE TEMPERATURE TO ABOUT 250*C. 